The opposed forces of differentiation and admixture across glacial cycles in the butterfly Aglais urticae

• Published in: Molecular Ecology
• Main Authors: Marques, Valéria, Hinojosa, Joan Carles, Dapporto, Leonardo, Talavera, Gerard, Stefanescu, Constantí, Gutiérrez, David, Vila, Roger
• Other Authors: Ministerio de Ciencia e Innovación (España), Generalitat de Catalunya, Università degli Studi di Firenze, Ministero dell'Ambiente e della Tutela del Territorio e del Mare
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: John Wiley & Sons 2024
• Subjects: Aglais urticae; Gene flow; Glacial cycles; Isolation; Relict lineages; Arctic
• Online Access: http://hdl.handle.net/10261/352423; https://doi.org/10.1111/mec.17304

Glacial cycles lead to periodic population interbreeding and isolation in warm-adapted species, which impact genetic structure and evolution. However, the effects of these processes on highly mobile and more cold-tolerant species are not well understood. This study aims to shed light on the phylogeographic history of Aglais urticae, a butterfly species with considerable dispersal ability, and a wide Palearctic distribution reaching the Arctic. Through the analysis of genomic data, four main genetic lineages are identified: European, Sierra Nevada, Sicily/Calabria/Peloponnese, and Eastern. The results indicate that the Sardo-Corsican endemic taxon ichnusa is a distinct species. The split between the relict lineages in southern Europe and the main European lineage is estimated to have happened 400¿450 thousand years ago, with admixture observed during the Quaternary glacial cycles, and still ongoing, albeit to a much smaller extent. These results suggest that these lineages may be better treated as subspecific parapatric taxa. Ecological niche modelling supported the existence of both Mediterranean and extra-Mediterranean refugia during the glacial periods, with the main one located on the Atlantic coast. Nevertheless, gene flow between populations was possible, indicating that both differentiation and admixture have acted continuously across glacial cycles in this cold-tolerant butterfly, generally balancing each other but producing differentiated lineages in the southern peninsulas. We conclude that the population dynamics and the processes shaping the population genetic structure of cold-adapted species during the Quaternary ice ages may be different than those classically accepted for warm-adapted species. This research was supported by grants PID2019-107078GB-I00 and PID2022-139689NB-I00 (funded by Ministerio de Ciencia e Innovación (MCIN)/Agencia Estatal de Investigación (AEI)/10.13039/501100011033 and ERDF A way of making Europe) and by grant 2021-SGR-00420 from Departament de Recerca i Universitats de la ...